Chromatin-based mechanisms of dynamic gene expression/repression

• Antragsteller: Professor Dr. Tilman Borggrefe
• Fachliche Zuordnung: Allgemeine Genetik und funktionelle Genomforschung
• Förderung: Förderung von 2012 bis 2016
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 211400705

• Erstellungsjahr: 2017

Zusammenfassung der Projektergebnisse

The project elucidated chromatin-based mechanisms of gene regulation by the conserved Notch signaling pathway. Upon ligand binding, the nuclear factor RBP-J activates transcription of target genes whereas in the absence of signaling, RBP-J switches off target genes expression by assembling a corepressor complex. In this project, we determined the molecular mechanism of how histone acetylation and methylation at Notch target genes are dynamically regulated. RBP-J, via its cofactor SHARP, recruits opposing complexes, the HDACs-containing NCoR corepressor complex and the KMT2D/UTX coactivator complex, which competitive recruitment is controlled by phosphorylation of chromatin modifiers. In addition to the lysine methyltransferase KMT2D, we discovered that an arginine methyltransferase, CARM1/PRMT4, is a Notch modulator. CARM1 is part of the Notch coactivator complex and directly methylates the intracellular domain of the Notch1 receptor (NICD1) at five conserved arginine residues within its activation domain. A methylation-defective NICD1 5RA mutant shows impaired ubiquitination and increased stabilization. Surprisingly, the stabilization of the NICD1 RA mutant does not result in a significant increase of its transcriptional activity compared to wildtype NICD1. Based on our biochemical and functional results, we developed a mathematical model wherein the normal NICD1 produces a short, strong transcriptional pulse, whereas the methylation-defective NICD1 mutant results in a weaker but prolonged response. Together, we propose that the above chromatin modifiers are potential targets for Notch-mediated diseases such as leukemia.

Projektbezogene Publikationen (Auswahl)

• Chromatin Immunoprecipitation (ChIP) in mouse T-cell lines. Journal of Visualized Experiments (124)
  Giaimo, B.D., Ferrante, F., Borggrefe, T.
  
• RNA helicase Ddx5 and the noncoding RNA SRA act as coactivators in the Notch signaling pathway (2013). Biochim Biophys Acta 1833(5):1180-9
  Jung, C., Mittler, G., Oswald, F., Borggrefe, T.
  
• 2014. Probing the epigenetic status at Notch target genes. Methods Mol Biol. 2014;1187:255-76
  Liefke, R, Borggrefe, T
  
• The tumor suppressor Ikaros shapes the repertoire of Notch target genes in T-cells (2014) Science Sign. 7:(317)
  Geimer Le Lay AS, Oravecz A, Mastio J, Jung C, Marchal P, Ebel C, Dembélé D, Jost B, Le Gras S, Thibault C, Borggrefe T, Kastner P and Chan S
  
• (2015) Site-specific methylation of Notch1 controls amplitude and duration of the Notch1 response. Science Sign. 8(369):ra30
  Hein, K., Mittler, G., Cizelsky, W., Kühl, M., Ferrante, F., Liefke, R., Berger, I.M., Just, S., Sträng, J., Kestler, H., Oswald, F., Borggrefe, T.
  
• (2016) A phospho-dependent mechanism involving NCoR and KMT2D controls a committed chromatin state at Notch target genes. Nucleic Acids Research, 44(10):4703-20
  Oswald, F., Rodriguez, P., Giaimo, B.D., Antonello, Z., Mira, L., Mittler, G., Thiel, V., Collins, K., Tabaja, N., Cizelsky, W., Radenz, M., Kühl, S., Kühl, M., Ferrante, F., Hein, K., Kovall, R., Dominguez, M., Borggrefe, T.
  
• . 2016. Setting the Stage for Notch: The Drosophila Su(H)-Hairless Repressor Complex. PLoS Biol. 14(7):e1002524
  Borggrefe, T, Oswald, F
  
• 2016. The Notch intracellular domain integrates signals from Wnt, Hedgehog, TGFβ/BMP and hypoxia pathways. BBA 1863(2):303-13
  Borggrefe, T., Lauth, M., Zwijsen, A., Huylebroeck, D., Oswald, F., Giaimo, B.D.
  
• (2017) Dll4 and Notch signalling couples sprouting angiogenesis and artery formation. Nature Cell Biology
  Pitulescu, M.E., Schmidt, I., Giaimo, B.D., Antoine, T., Berkenfeld, F., Ferrante, F., Park, H., Ehling, M., Biljes, D., Rocha, S.F., Langen, U.H., Stehling, M., Nagasawa, T., Ferrara, N., Borggrefe, T., Adams, R.H.
  
• (2017) Heterodimerization of AML1/ETO with CBFβ is required for leukemogenesis but not for myeloproliferation. Leukemia
  Thiel, V., Giaimo, B.D., Schwarz, P., Sollner, K., Vas, V., Bartkuhn, M., Blätte, T., Döhner, K., Bullinger, L., Borggrefe, T., Geiger, H., Franz Oswald
  
• Dynamic chromatin regulation at Notch target genes. Transcription 2017 Jan;8(1):61-66
  Giaimo, B.D., Oswald, F., Borggrefe, T.